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Method for removing boron and metal impurities for polysilicon melting in electron-beam furnace

An electron beam furnace and metal impurity technology, applied in chemical instruments and methods, non-metallic elements, silicon compounds, etc., to achieve the effect of improving the ability of volatilization and removal of impurities

Active Publication Date: 2014-02-19
宁夏宁电光伏材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] So far, there is no way to overcome the above drawbacks

Method used

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  • Method for removing boron and metal impurities for polysilicon melting in electron-beam furnace

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Effect test

Embodiment 1

[0022] Embodiment 1: A method for removing boron and metal impurities by smelting polysilicon in an electron beam furnace, characterized in that: the method is: take boron content of 0.25ppmw, phosphorus content of 9.08ppmw, iron content of 0.47ppmw, copper content of 0.03ppmw Silicon block, the particle size of silicon block is less than 25mm. The silicon block is acid-washed with a mixed dilute solution of hydrochloric acid and hydrofluoric acid, and a pure water lotion is used to test the conductivity of the pure water after the lotion is close to the conductivity of the pure water, and the lotion is completed.

[0023] Put the lotioned silicon block into a high-temperature resistance furnace, rapidly raise the temperature to 600°C at a rate of 5°C / min, keep it warm for 4 hours, stop heating, and cool down naturally. When the furnace temperature drops to room temperature, stop the furnace and discharge. A light blue color appears on the surface of the silicon block, indicat...

Embodiment 2

[0027]Embodiment 2: A method for removing boron and metal impurities by electron beam furnace smelting polysilicon, characterized in that: the method is: take boron content of 0.25ppmw, phosphorus content of 9.08ppmw, iron content of 0.47ppmw, copper content of 0.03ppmw Silicon block, the particle size of silicon block is less than 25mm. The silicon block is acid-washed with a mixed dilute solution of hydrochloric acid and hydrofluoric acid, and a pure water lotion is used to test the conductivity of the pure water after the lotion is close to the conductivity of the pure water, and the lotion is completed.

[0028] Put the lotioned silicon block into a high-temperature resistance furnace, rapidly raise the temperature to 900°C at a rate of 5°C / min, keep it warm for 2 hours, stop heating, and cool down naturally. When the furnace temperature drops to room temperature, stop the furnace and discharge. A light blue color appears on the surface of the silicon block, indicating tha...

Embodiment 3

[0032] Embodiment 3: A method for removing boron and metal impurities by smelting polysilicon in an electron beam furnace, characterized in that: the method is: take boron content of 0.25ppmw, phosphorus content of 9.08ppmw, iron content of 0.47ppmw, copper content of 0.03ppmw Silicon block, the particle size of silicon block is less than 25mm. The silicon block is acid-washed with a mixed dilute solution of hydrochloric acid and hydrofluoric acid, and a pure water lotion is used to test the conductivity of the pure water after the lotion is close to the conductivity of the pure water, and the lotion is completed.

[0033] Put the lotion-treated silicon block into a high-temperature resistance furnace, rapidly raise the temperature to 900°C at a rate of 5°C / min, keep it warm for 3 hours, stop heating, and cool down naturally. When the furnace temperature drops to room temperature, stop the furnace and discharge. A light blue color appears on the surface of the silicon block, i...

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Abstract

The invention relates to a method for removing boron and metal impurities for polysilicon purification, in particular to a method for removing boron and metal impurities for polysilicon melting in an electron-beam furnace. The method is characterized in that silicon briquettes as the raw materials firstly are subjected to acid pickling and washing, and are then placed in a high-temperature resistance furnace for high-temperature oxygenation pre-processing; the processed silicon materials are fed into a three-gun electron-beam furnace for melting; after the melting, the silicon ingots are taken out after the temperature is reduced to the room temperature; the skins and bottom layers are removed, the loose layer, where metal impurities are concentrated, of the core at the upper end of each silicon ingot is gently knocked off through a hard alloy hammer, and then solar polysilicon is obtained. The method provided by the invention is unique; through the adoption of the method, not only are phosphorus and metals such as calcium and sodium are removed, but also has very remarkable effects for removing boron and iron, copper and other metal impurities; the method has the advantages of high impurity removal efficiency, large yield and remarkable economic effects.

Description

technical field [0001] The invention relates to a method for purifying polysilicon to remove boron and metal impurities, in particular to a method for electron beam furnace smelting polysilicon to remove boron and metal impurities. Background technique [0002] The photovoltaic industry is an emerging sunrise industry and an innovative green industry. At present, the solar cell market is dominated by monocrystalline silicon and polycrystalline silicon cells, accounting for more than 85% of the total solar cells. As the basic material of crystalline silicon cells, solar-grade polysilicon is in increasing demand with the rapid development of the solar photovoltaic industry. The production methods of polysilicon mainly include: improved Siemens method, silane method, metallurgical method, etc. Among them, the polysilicon produced by the improved Siemens method and the silane method has a higher purity, and the purity can reach between 9 and 11 nines. When it is used as a sola...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 蒋宁雄盛之林梁庆侯宝锋蒋学萍杨永浩吴佳楠
Owner 宁夏宁电光伏材料有限公司
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